What should organisations do when users have many old accounts with the same password?

Why repeated passwords create a security problem

When many old accounts share the same password, the real issue is not convenience, it is blast radius. If one site, email inbox, or legacy system is exposed, attackers can try the same password elsewhere and quickly turn a single weak point into broader account compromise. The risk increases when those accounts still have active access, recovery paths, or stored personal data.

Because old accounts often linger unnoticed, they also weaken incident response. You may not know which systems still accept the password, which services have been abandoned, or which accounts are tied to a person who has changed role or left the organisation. That makes password reuse both an exposure problem and an inventory problem.

How a phased remediation plan should work

The practical fix is to move in stages rather than trying to reset everything at once. Start with the highest-value or most exposed services, especially those with administrative access, customer data, finance, or external authentication. Then work through the remaining accounts in small groups so users can update credentials without being overwhelmed or pushed into unsafe workarounds.

This approach is effective because it lowers risk early while preserving momentum. It also gives teams room to validate ownership, retire dead accounts, and identify where a password is duplicated because of shadow IT, shared access, or forgotten dependencies. Where possible, pair the cleanup with account disablement, single sign-on, or stronger authentication so the same problem does not return.

For longer-lived legacy systems, the plan may need exception handling. Some platforms cannot change authentication cleanly without application changes, vendor support, or user migration. In those cases, document the constraint, isolate the account, and treat the remaining shared-password exposure as temporary technical debt with a deadline, not as an accepted steady state.

What organisations should verify before and after cleanup

Before remediating, confirm which accounts are still active, which are tied to privileged functions, and which can be safely removed instead of reset. That distinction matters because changing a password on an account that should already be gone only preserves unnecessary exposure. It is also worth checking whether the same password is reused across external services, internal tools, and recovery channels.

After each wave, verify that the changed accounts no longer authenticate with the old password and that the owner can still access the service by the approved path. If the organisation tracks authentication logs, monitor for repeated failed attempts against the retired credentials, because that may indicate an attacker already has the password or is probing for reused accounts.

Practitioner Guidance

What to prioritise: Start with the accounts that would do the most harm if reused or compromised, such as admin accounts, finance systems, support consoles, and externally reachable services. Low-value accounts can wait until the high-risk set is reduced.

Decision rule: If an account still has access to production, customer data, or privileged functions, treat it as a remediation priority even if the user rarely touches it. If the account is no longer needed, disable or delete it instead of resetting the password.

What to verify: Confirm ownership, last use, and business need before changing credentials. The common mistake is to reset old accounts without deciding whether they should exist at all, which preserves clutter and delays real risk reduction.

Practitioner takeaway: The goal is not a one-time password purge, but a controlled reduction in blast radius, one account set at a time, until reused credentials are no longer a practical path for lateral movement.

Related resources from NHI Mgmt Group

• How should organisations apply NIST password guidance when users manage many accounts across work and personal systems?
• Why do differentiated identity and password policies matter in organisations with staff, privileged accounts, and franchise users?
• How can organisations reduce the risk of stale API keys and machine tokens?
• How should teams reduce the risk of orphaned service accounts and stale tokens?